Method and means for patching veneer and manufacturing paper-overlaid veneer



Nov. 3, 1964 c. c. cLAPP METHOD AND MEANS FOR PATCHING VENEER ANDMANUFACTURING PAPER-OVERLAID VENEER 2 Sheets-Sheet 1 Filed April 6, 1959xom 295mm mwoiomu Q\ INVENTOR. (7/4565? C. (ZAP/ NOV. 3, 1964 c, c CLAPP3,155,558

METHOD AND MEANS FOR PATCHING VENEER AND MANUFACTURING PAPER-OVERLAIDVENEER Filed April 6, 1959 '2 Sheets-Sheet 2 INVENTOR. 644E155 C, (ZAP/9A r role/vfl United States Patent 3,155,558 METHOD Ahll) MEANS FQRPATCHING VENEER AND MANUFACTURENG PAPER OVERLAID VENEER Qharles C.Clapp, Tacoma, Wash, assignor to Weyerhaenser Company, Tacoma, Wash, acorporation of Washington Filed Apr. 6, i959, Ser. No. soaaaz (Ilaims.(Cl. 15694) This invention relates to a new and improved process andapparatus for patching or plugging holes in wood veneer and to animproved process for manufacturing veneer in which such patchingarangernents are employed to unique advantage. The invention is hereinillustratively described by reference to the presently preferred formand mode of operation thereof; however, it will be recognized thatcertain modifications and changes therein with respect to details may bemade without departing from the underlying features involved.

In the manufacture of veneer and similar products using wood veneer asthe base and using paper, fabric or other sheet material as a coverlayer, usually on both faces, it is important that a grade of veneer bechosen having no large knots or unfilled knotholes. If the over-alldiameter of a knot and immediately surrounding region of very densegrain exceeds about one inch it is very difficult to achieve a goodadhesive bond between the wood and the overlay sheet in that area. Thisis particularly so with thermoactive cements, as used in most case.Therefore, in order to upgrade reject or inferior veneer satisfactorilyfor this and similar applications, it is necessary to remove the largeknots and immediately surrounding dense grain regions, and then to fillthe resulting holes, as well as to fill any other holes in the veneer. To be most economical and practical the patching should be executed in arapid and substantially continuous machine operation, and in this caseone which is readily integrated into a veneer production system. Thefiller material used should produce in the completed product a strongand durable patch which adheres well both to the surrounding hole edgesand to the adhesively coated overlay sheets. In the final product thepatch, though concealed by the cover, must nevertheless possess asubstantial degree of hardness, with toughness and a certain flexiblityso that it will compare favorably with the characteristics of thesurrounding Wood making up the veneer core. The raw materials used inpatching should, of course, be readily available as well as inexpensivematerials.

In broad terms the invention is concerned with the attainment of theforegoing objectives. In so doing, however, it is particularly concernedwith avoiding certain difficulties which develop in connection with aprior proposal for machine patching of veneer. In that proposal finelyparticulated thermoactive material in a powdery and almost dustlikereadily airborne state was partially blown by air and partially drawnand held by suction, against a carrier screen or backing supporting theveneer itself, in order to fill the holes or openings in the veneersheet. It was necessary to substantially overfill or heap material inand upon the cavities in each instance in order to obtain the necessarydensity and solidity of the final patches which resulted when thematerial was compacted to the level of the veneer surface and activatedby heat. One difiiculty with such a process was that of preventingexcessive spreading and overflow of the powdery and readily shiftablematerial beyond the hole edges, aggravated or caused by transferal ofthe veneer onto a succeeding conveyor prior to any substantialactivation or setting of the fill material.

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The unavoidable result, therefore, was the presence of lumps and ridgessurrounding the patches themselves, thereby impairing the quality of theproduct or necessitating subsequent sanding or scraping operations toremove the excess following curing of the patches. Uniform patches weredifficult to achieve with that proposed process and the same is not Wellsuited for integration into a rapid and continuous machine patchingoperation nor into a production system for veneer.

It is a further and more specific object of the in- Vention to provide amachine patching apparatus and process generally overcoming theabove-mentioned and other difficultiesand limitations in the priorproposals and particularly the problem of lumps or ridges left adjacentthe hole edges by overflow patching material. Also the invention isconcerned with improving the patch characteristics and attaining highrates of production of patched veneer and of vener incorporating thepatched veneer.

Another object is to provide such a process and apparatus whereincertain operations are combined in order to save space, and the cost ofcomponents as well as the cost of thermal energy. Thus final activationof the patch material and activating of the adhesive coating on thepaper or other covering layers as the latter is being applied to thepatched veneer are combined to particular advantage. While with themethod disclosed surface projections of patch material resulting fromthe initial phases of the patching operation are minimal, and occur ifat all substantially within the projected outlines of the holes oropenings being filled, the same are readily eliminated in a combinedprocess of heat-bonding the paper overlay sheets and at the same timeremolding and ironing out the patches.

In accordance with additional features of the invention thermoactive,preferably thermoplastic patch material is utilized and is partiallycured or set by heat before leaving the suction field of the carrierscreen, particularly so that the surface or side of the patch oppositethe screen is activated to form a retaining crust. In the processthereof it is found that the material shrinks somewhat in volume, withinthe projected outline of the patch hole edges, and substantially closerto the contiguous surface level of the veneer. Because of relativelydense granulated type of material is used in the first instance,requiring very little overfilling of the hole in order to produce therequisite patch density upon compaction to surface level there is noappreciable spreading or spilling of the material beyond the hole edgesto cause objectionable lumps and ridges on the surface of the veneer.The opposite side or surface of the patch upon leaving the field of thesuction carrier screen is already substantiaily at veneer surface levelbecause of the coplanar relationship between the two caused by theircontact with a common backing surface, namely the screen. Consequently,as the preliminarily secured patch advances into a subsequent or finalcuring operation which in the preferred instance is the cover paperapplication, there is no appreciable problem with spillage or overflowof patch material, yet adequate patch material is present in all of theholes for final curing when the thermoactive paper-coating adhesiveitself is cured for bonding the paper to the veneer. Such a process andapparatus avoids serious problems of cleaning the suction carrier screenbecause of the fact that the patching material in contact with thescreen is not cured or activated while on the screen, but after leavingit. With the invention, knotholes and any other openings or gaps betweenadjoining sheets of veneer are uniformly and rapidly filledautomatically as the veneer sheets are crowded in successiveedge-abutted relationship to the apparatus in a continuous productionline flow. Heated rolls are preferably used as the heat and pressureapplying means bonding the paper to the veneer surfaces and remoldingand finally curing the patches in conjunction with the assembly of theveneer layers -to produce a strong, smooth-surfaced, durable and highquality product, starting with normal reject or waste veneer stock.

These and other features, objects and advantages of the inventionincluding the details of the preferred and illustrated embodimentthereof will become more fully evident from the following description byreference to the accompanying drawings.

FIGURE 1 is a simplified side elevation view illustrating the processand the preferred form of apparatus for patching veneer andmanufacturing veneer in accordance with this invention.

FIGURE 2 is a side elevation view of a preferred form of a portion ofthe machine illustrated in a practical working form.

FIGURE 3 is a top view of the same machine.

FIGURE 4 is an enlarged longitudinal sectional view of that portion ofthe machine by which the granulated material is initially applied to theholes to be patched.

FIGURE 5 is an enlarged sectional end view showing a side portion of themachine and supplementing the showing of FIGURE 4 of the patchingmaterial applicator, the view being taken in a vertical plane throughthe applicator bin parallel to the applicator shaft.

Referring to the drawings, particularly to FIGURE 1 at the outset, cutveneer strips V are delivered in rapid succession by a feed conveyor 60to a crowder conveyor comprising a plurality of parallel conveyor chains10a encircling sprockets 10b. Slightly overlapping the discharge end ofthe crowder conveyor 10, is the receiving end of the suction-screen orpatching conveyor 12 comprising the wide, endless wire mesh screen belt12:: encircling the driving and driven guide rolls 12b and 12c spacedapart in parallel relationship along the desired direction ofconveyance. The lineal speed of the crowder conveyor chains 1011 arecaused to slightly exceed that of the patching conveyor belt 12a so asto permit the crowder conveyor to advance the oncoming sheets intotightly edge-abutted relationship with those which immediately precedethem in reaching the lower surface of the lower stretch of the patchingconveyor screen belt, which is its active conveying surface.

Within the space defined and encircled by the patching conveyor 12 is anenclosed suction box 14 having a perforate lower side serving as abacking and guide for the lower stretch of the belt. Openings 14a in theperforate lower side of the suction box are distributed more or lessuniformly over its surface. Suction is applied to the interior of thesuction box 14 through a suction tube 14b from a source (not shown), thesuction tube 14b joining the suction box 14 through a widened throat 14bwhich assures substantially uniform distribution of suction over theopenings 14a. Once the veneer sheet comes into overlap with the suctionbox and into the field of suction communicated and evenly distributedthrough the screen mesh, the veneer is held flatly against the screen asa result of the vacuum. It remains suspended horizontally in this manneruntil it is deposited or transferred into supported contact on the lowersheet of paper or other covering material 16:: being continuouslysupplied and drawn from the supply roll 16, as shown.

Just beyond the discharge end of the crowder conveyor 10 is situated apatching material applicator 18 by which a shower of granulated patchingcomposition is thrown in quantity against the lower surface of theveneer with substantially uniform density across its entire width, as itadvances on the conveyor screen belt 12a beneath the suction box 14.Where this particulated material strikes solid areas on the veneer, itsimply falls back into the container of the applicator 18. However, dueto the suction applied through the multiply apertured lower plate of thesuction box 14 and distributed uniformly by the metal belt 12a, thematerial which is thrown into an opening or hole in the veneer is heldthere and accumulates to overfill the hole. To assure complete fillingof all of the holes and openings, an excess quantity of material is, ofcourse, projected against the veneer. The excess actually accumulated asfill in each hole or opening in the veneer is removed and the pileleveled off by a scraper 18a as the veneer in its advance passes beyondthe edge of the applicator. In fact, as later explained more fully, withthe type of fill material preferably used in the process very littleexcess fill is required beyond the thickness of the veneer itself inorder, when compacted and activated, to form an ultimately solid anddurable patch. During the further advance of the veneer the resultingproper measure of fill material is held by the suction in each openingto be patched as long as the veneer sheets are carried on the patchingconveyor and are within the field of suction.

Prior to leaving the field of suction established by the suction boxthrough the distributive action of the screen, and in accordance with animportant feature of the invention, the lower side or surface region ofeach fill is activated and thereby solidified or semi-solidiied, as bypassing the veneer over a heat source 20. The amount of heat applied ispreferably sufiicient to form a retentive crust on the lower surface ofthe granulated material fills so as to retain the remainder of thematerial in the patch openings. Excess heat is avoided so as to preventactivating the upper surface regions and causing fusion and sticking ofthe material to the screen itself which could plug the screen and createserious cleaning problems as well as pulling needed fill material fromthe patch openings. Application of heat from the source 20 not only setsup a solid or semi-solid crust on the lower side of the body ofgranulated filler material occupying the openings or holes in the veneerbut causes a certain substantial amount of shrinkage of that materialwhich will draw much of it up into the confines of the hole and closerto the lower surface plane of the veneer itself.

In the veneer application disclosed, upon leaving the heater 20 and upondischarge from the field of suction the sheets, with at least partiallyset or solidified patches, continue their advance onto a continuouslyfed bottom surfacing sheet of paper 16a which passes through an adhesive spreader consisting of a glue trough 9, a pick-up roll 8, anapplicator roll 7 and a backup roll 6, and slides on a guide platen 22.A top surfacing sheet of paper 24a unwinding from a supply roll 24 isfed through a similar adhesive spreader consisting of a glue trough 9a,a pickup roll 8a, an applicator roll 7a and a backup roll 6a, and intocontact with the upper surface of the advancing veneer sheets. Theveneer, covered on both sides by the paper sheets, then passes betweenmeans to fully activate and solidify the patches and preferably at thesame time activate the adhesive coating on the paper and press thelatter into bonding contact with the veneer surfaces. The compressorrolls 26 .and 28, at least one of which is heated and one of which ispreferably driven, accomplish this in highly simple and effectivemanner. The upper roll may be mounted on a suitable support permittingthe weight thereof to provide the necessary pressure. At this time anyirregularities or excesses of granulated fill material projecting beyondthe surface planes of the sheet within the hole outlines are ironed outby the applied heat and pressure to impart an externally smooth andflat, finished surface effect.

It will be evident that in this manner the openings or holes H in theveneer sheets though occurring in varying sizes, shapes and locationswill be treated alike and uniformly patched. In a continuousedge-abutted run of the sheets as in the illustrated veneermanufacturing arrangeswans ment any unevenness or jogs in the edges 1,which would otherwise form gaps in the veneer core, will also be patchedalong with the holes formed by knots and from other causes.

For convenience in maintaining the desired tension in the wire screenbelt 12a the idler roll 12c thereof is mounted on pillow blocks 30 whichmay be moved lengthwise of the machines, toward and from the axle 32carrying the opposing driven roller 12b. Take-up-adjustment is effectedby means of the positioning bolts 34 and nuts 36 which bear against afixed support 33 comprising part of the machine frame. The suction box14 is mounted between frame bars 40 by anchor bolts 4?. which may beloosened in order to permit raising or lowering the suction box anynecessary amount for a close adjustment of its position in relation tothe desired guide plane for the lower, active stretch of the conveyorscreen. To this end the frame side bars 40 have vertical slots 44 whichaccommodate the bolts 42.

A geared motor unit 46 having an output gear 48 provides the drive powerfor the complete conveyor system. A drive chain 50 passing around thedrive gear 48 also engages a pinion 52 on the drive shaft 32 of roll 12band passes around a pinion 54 drivingly connected to the sprocket shaftfor the crowder conveyor 10. Finally such chain completes its drivecircuit in passing around the sprocket 56 on the drive shaft of theheated compression roller 28 as shown. The appropriate speed ratios areachieved by selecting proper sprocket sizes and the appropriate relativedirections of turn of the driven shafts are determined by the manner inwhich the chain engages the associated sprockets. Preferably the veneersheets are supplied to the crowder conveyor from any suitable inputconveyor such as the chain conveyor 60 shown in FIGURES 2 and 3.

The fill material applicator 18, which throws the material against theveneer preferably comprises a mechani cal type device as distinguishedfrom a type relying solely on air currents, since relatively dense andheavy particulated fill material is used in the preferred technique ofthe invention. As shown in FIGURE 4 the illustrated applicator comprisesan elongated hopper or bin 64 which extends the full width of themachine or of the veneer and contains a supply of the granulated fillmaterial G. An agitator or flinger unit is mounted for rapid rotation inthis hopper on a horizontally disposed shaft 66 extending transverselyto the line of conveyance. The shaft 66 is driven at relatively highspeed by a suitable drive source (not shown), acting in this instancethrough a V-belt 75 and pulley '78. Paddles or arms 66a are mounted atlongitudinal intervals and at circumferentially spaced points on theshaft 66 and pick up quantities of the material and throw it against theunder side of the advancing veneer sheet so that the openings H thereinwill be filled as shown at F. Slight forward curvature or canting of theouter end portions of these arms in the direction of rotation increasestheir efiiciency to pick up the material from the bottom of the bin andcarry it upwardly for discharge against the veneer. The bin isconstantly or intermittently supplied with fresh granulated materialfrom a suitable feed source (not shown) through the duct or ducts 68.With agitator arms approximately two inches long (i.e., overall diameterof approximately four inches) a shaft speed of approximately 290 rpm.proves to be satisfactory. Speeds much below this value cause the finesize particles to produce some clogging of the screen and reduce theamount of material that could be held by suction in the veneer openings.At this speed and with the materials Yo be described the machine provescapable of patching at a rate of 35 to 40 feet per minute which is adequate since it somewhat exceeds the usual rate at which veneer can besatisfactorily fed to the crowder conveyor 10.

As previously mentioned, with relatively dense and incompressible fillmaterial only a slight excess of fill beyond the actual thickness of theveneer itself is required in order to form the patches. The preciseamount required is gauged by close adjustment of the scraper 18a whichprojects upwardly from the down-travel side of the bin 64. This scraperpreferably comprises a somewhat flexible member such as a rubber bladewhich will not catch or hang up a veneer sheet and stop its advance incase it accidentally carries a projecting burr or the like. This bladeis adjusted to the desired height in relation to the lower surfaceelevation of the veneer which in a typical case will allow aboutone-sixteenth of an inch overfill with three-sixteenths inch thickveneer, and in approximately the same proportion on thicker or thin nerveneers depending upon the fill materials used and the heats andpressures applied. The scraper blade also incidentally serves as a sealminimizing escape of particles beyond the confines of the bin at thedischarge side of the bin. A rubber wiper blade 72 on the input side ofthe bin performs a similar function at that location, so that verylittle of the material is wasted. A screw 74 and clamp strip 76 holdsthe scraper 18a in position and the screw may be loosened in order topermit vertical adjustment of the scraper, as by providing verticalslots (not shown) in the hopper wall at the location of each of thescrews 74. A similar arrangement is provided in connection with thewiper 72.

With reference to the suction box 14, the sizes and locations of theopenings or apertures 14a in the bottom plate thereof are notparticularly critical in view of the effect of the wire screen belt 12ain distributing and equalizing the force of suction applied throughoutthe area of the screen belt in contact with the veneer sheets. Theinterstices in the wire screen provide this function while at the sametime the flexible screen backed by the rigid bottom panel of the suctionbox maintains a substantially rigid and flat backing surface againstwhich the veneer is held by the suction during the patching operation. Asuction of the order of six inches of water is considered adequate toperform the functions required.

The carrier screen belt 12a may be of a suitable wire or equivalent meshmaterial having a mesh opening size which will prevent passage of fillmaterial particles into the suction box, yet provide the desireddistribution of suction over the surface of the veneer. In a typicalcase the wire screen used has 0.008 inch warp and 0.0095 inch fillerwire diameter with open spaces of 0.0063 inch times 0.0084 inch.Excessively heavy gauge wire presents problems in tearing due to fatiguefailure as the wire continues to travel in a bend around the rollersover a long period of use. In another case a 55 mesh (0.01075 inch wirediameter) times 40 mesh (0.012 inch wire diameter) bronze Fourdrinierwire screen with pin seam proved successful.

The principal or pre-cure heater unit 20 may assume different forms andin its preferred form, intended for high rates of production wherein theveneer sheets advance quite rapidly through the heating zone, preferablyrelies, primarily at least, on heated air currents to fuse or set thelower portions of the patch fills. One suitable heating arrangement forthis purpose is represented by the insulating casing or shield 20::which prevents excessive heat radiation against the bin 18, for example,where it would prematurely set up the stored granular fill material, andalso confines the heat to the working area. Calrod electrical heaterunits 20!: are mounted in this casing and openings 200 are afforded inthe bottom thereof to permit air to rise into contact with these units.Baffles 20d prevent direct radiation of heat against the veneer andinsure the maximum conversion of energy into the heating of the risingair currents which thereafter flow into contact with the material. Thisassures shallow but quick surface heating of the patch fills in order toform the desired crust at the bottom thereof without excessivepenetration to the upper regions in contact with the carrier screen.Thermostatically controlled air, heated in this manner to about 220degrees Fahrenheit proved effective to heat and fuse the lower portionsof the patches with the material used as hereinafter described. Asuitable thermostatic control (not shown) controls the air temperature.Radiant heating methods may be used if desired but more exact andcritical control thereof is usually necessary to assure effective andsufficient heating of the lower surface region of the patches withoutfusing the upper regions thereof so as to cause the material to stick tothe screen.

As previously indicated, the initial heat application effected while theveneer fills are still in the suction field not only assures theeventual confinement of the granulated and unfused portions of the patchmaterial in the openings to be patched but causes some contraction ofthe excess which projected beyond the plane of the veneers lower face.Consequently the fill material will not tend to shift or sift out ofplace and initial contact of the lower side of the fills with the paper16a overlying the platen 22 will not press and spread out the granulatedmaterial beyond the edges of the opening at the lower side of the sheetnor will it displace the fills upwardly in relation to the veneer andcause the material to spill over the sides of the opening at the topface to cause eventual lumps or ridges on the veneer surface. Ifdesired, prior to contacting the top surfacing paper sheet,thermoactivation of the upper regions of the fill material may beeffected by suitable means such as a radiant source means represented bythe battery of infrared lights 25 stationed just beyond the patchingconveyor 12 and ahead of the point of introduction of the top coversheet 24a as shown (FIG. 1).

It is usually desirable, despite the minimal tendency to activate fillmaterial in contact with the carrier screen 12a to provide some meansassuring that the screen will be kept quite clean of accumulations ofgranulated patching material. One effective arrangement for this purposecomprises a suction hood 80 overlying the upper or return stretch of thescreen with a rotary bristle brush 82 constantly rubbing against thescreen in order to dislodge or loosen any adhered particles. A force jetor jets 84 situated directly beneath the screen blows upwardly into thesuction hood 89 the loosened particles where they are carried awaythrough the suction conduit 86 connected to any suitable source ofsuction.

The patching compound or composition selected for the purpose shouldhave certain desirable characteristics as mentioned above including thatof forming a good adhesive bond with the veneer hole edges and with thebonding adhesive which is used to bond the cover sheets 16a and 24a tothe veneer itself. Moreover, such material is preferably thermoplasticas distinguished from thermosetting so that even the preliminarilyencrusted or set lower portions of the patches may be remolded if and asnecessary when the paper covers are being pressed and heated in contactwith the veneer. This capability of softening again under heat assures asmoother exterior surface finish free of lumps and also assuresobtaining a stronger bond between the patch material and the paper whichcovers it on both sides. A preferred material for this use comprises amixture of thermoplastic substance such as a resin with a suitableextender such as a bark fraction extender. Successful results have beenachieved with a composition mixture of 45% by weight of a hard, brittle,dark-colored, non-crystalline thermoplastic resin which is 60% gasolineinsoluble, which has a melting point of 187 F. and a flash point of 410F., which has an acid number of 119 and a specific gravity of 1.138 at20 C., and which is soluble in ethyl acetate, alcohol, acetone, aromatichydrocarbons, and is partly soluble in aliphatic hydrocarbons, carbontetrachloride, and is compatible with ethyl cellulose, and 55% of aselected Douglas fir bark powder fraction having as constituents, ligninlike polyphenols with tannins, natural waxes, and resins present in fairquantity. Intermixed, the bark extender and resin are heated and rolledout as a thin sheet, then cooled. This hard sheet is then ground to formparticles similar to ground coffee or sand and screened to take out theextremely coarse and fine particles. The overly coarse or excessive fineparticles are of course reusable in the forming of subsequent sheets tobe ground for achieving the desired particle size acceptable for use inthe disperser bin. Preferably the usable particle sizes are those in therange which will pass an approximately 14 mesh screen and not a 50 or 60mesh screen.

Other wood resins which may be used for the purpose would include ablack soda-treated rosin which has a melting point of 76 C. using theball and ring method, an acid number of 1.07, a saponification number of135, and has 22.5% unsaponifiable matter. The bark extender and thethermoplastic material used have a variety of suitable substitutes whichmay be used in their place but in choosing materials, economy should, ofcourse, be considered, as well as the necessary physical characteristicsdesired for the disclosed application. For example, experiments withsome success have been conducted with a mixture of sand and rosin,another dense and substantially homogeneous mixture which requireslittle compaction in order to form a solid patch. Coffee grounds provedusable though not as satisfactory as the preferred materials named. Thestep of fusing the material into a base stock which is subsequentlycomminuted assures an initial relatively high-density andlow-compressibility fill which requires very little compacting orcompression in volume in order to produce a strong and solid fillerpatch despite the fact that very little excess is left in the process ofpassing the veneer by the scraper blade 18a. Foamed plastic beads, suchas expandable polystyrene beads, may be used as the patching compound.It has been found desirable in using such materials to pre-expand anddry the beads. It is also advantageous to use an expandable beadcompound having a bulk density of 6 to 10 pounds per cubic foot afterexpansion.

The invention has thus been set forth in its preferred embodiment as anew and useful advance in the art of veneer patching and veneermanufacture. It will be recognized, however, that the disclosure isnecessarily based on examples which, taken alone, should not beconsidered as delimitative of the scope of the novel features andaspects represented.

I claim as my invention:

1. A continuous method of patching veneer to plug a hole thereincomprising the steps of applying a perforate external backing surface tothe upper face of said veneer,

applying a suction to said veneer through said external backing surfaceto maintain said veneer in contact with said backing surface, propellingparticulate thermoactive material upwardly from beneath said veneer tofill said hole in said veneer with enough of said material to completelyfill said hole when said material has been activated,

heating said material on the lower face of the veneer during theapplication of said suction to effect at least partial solidificationthereof at said lower face and to a limited depth terminating short ofsaid upper face in contact with said surface, removing said heat fromsaid lower face, continuing said suction during formation of a retentivecrust on said material, continuing said suction until said veneer isdeposited onto a lower support,

removing said suction and said perforate backing surface from saidveneer, and

further heating said material to activate said material in said hole,whereby a substantially solid plug is formed in such hole.

2. A continuous method of patching veneer to plug a hole thereincomprisinng the steps of applying a perforate external backing surfaceto the upper face of said veneer,

applying a suction to said veneer through said external backing surfaceto maintain said veneer in contact with said backing surface,

propelling particulate thermoplastic material upwardly from beneath saidveneer to fill said hole in said veneer with enough of said material tocompletely fill said hole when said material has been softened,

heating said material on the lower face of the veneer during theapplication of said suction to effect at least partial solidificationthereof at said lower face and to a limited depth terminating short ofthe upper face in contact with said surface,

removing said heat from said lower face,

continuing said suction during formation of a retentive crust on saidmaterial, continuing said suction until said veneer is deposited onto alower support,

removing said suction and said perforate backing surface from saidveneer, and

thereupon heating said material and pressing the veneer and the materialbetween external surfaces to activate and move the material at bothsides of the veneer, whereby substantially solid flush plugs are formedin said hole.

3. A continuous method of patching veneer to plug a hole thereincomprising the steps of applying a perforate external backing surface tothe upper face of said veneer,

applying a suction to said veneer through said external backing surfaceto maintain said veneer in contact with said backing surface, propellingparticulate thermoactive material upwardly from beneath said veneer tofill said hole in said veneer with enough of said material to completelyfill said hole when said material has been activated,

heating said material on the lower face of the veneer during theapplication of said suction to effect at least partial solidificationthereof at said lower face and to a limited depth terminating short ofsaid upper face in contact with said surface, removing said heat fromsaid lower face, continuing said suction during formation of a retentive crust on said material, continuing said suction until said veneeris deposited onto a lower support,

removing said suction and said perforate backing surface from saidveneer, and

further heating said material to activate said material in contact withsaid surface, whereby a substantially solid plug is formed in such hole,

applying therrnoactive adhesive coated top and bottom surfacing sheetsto said veneer, and

thereupon heating the fills and sheet and pressing the same betweenexternal surfaces to bind the sheets to the veneer and to activate andsmooth the fill material therein.

4. The method of claim 3 in which said thermoactive filling material isa thermoplastic material.

5. Apparatus for patching holes in veneer with particulated thermoactivefill material, comprising support means including an endless screen beltconveyor having a generally horizontal stretch and means mounted abovesaid stretch of screen to apply suction through the same to draw andhold the veneer sheet into contact with the lower side thereof over asurface area on the veneer including the area of holes to be patched,said suction applying means comprising a hood overlying the generallyhorizontal lower stretch of the screen and having a bottom side surfaceslidably contacted by said lower stretch and having suction openingstherein distributed over a substantial portion of the length and widththereof superimposed on said stretch of screen, the screen mesh openingsbeing smaller effectively than the size of said particulate material,applicator means for fill material stationed beneath said screen stretchand operable for applying particulated fill material to the veneer sheetto fill any holes in the veneer, said applicator comprising a bincontaining fill material extending transversely substantially the widthof the screen, an agitator means in said .bin including a rotatableshaft extending transversely of the screen and having arms thereondipping into the fill material in the bin and flinging such materialupwardly in a steady shower against the lower surface of the veneer asthe shaft rotates accompanying advance of the veneer on the conveyorscreen, heater means stationed beneath and spaced from said screenstretch at a relative location olfset from said applicator means to heatthe fills in the veneer superficially in the lower side thereof whileheld by suction on said screen, means to move the screen and thereby theveneer successively past said applicator means and heating means,auxiliary veneer support means stationed adjacent said conveyor screenand olfset from said heater means for receiving the veneer ontransferral from the latter, and heating means associated with saidauxiliary support means further to heat and cure the preliminarilyheated fills, including the upper sides thereof, to activate andsubstantially solidify the fill material therein.

6. The apparatus defined in claim 5, wherein the firstmentioned heatingmeans comprises a heat source, shield means surrounding said heat sourcehaving openings at top and bottom for passage of rising air currentsthrough said shield means to heat the veneers lower face in passing oversaid shield means and thereby heat the fills superficially.

7. The apparatus defined in claim 5, wherein the second-mentionedheating means and auxiliary support means comprise rollers at least oneof which is heated, between which the filled veneer sheets pass onleaving the conveyor screen.

8. The apparatus of claim 5 further comprising laminating conveyor meansstationed beyond the screen belt conveyor and beyond said heating meansand including means applying thermoactive-adhesive-coated coveringsheets progressively to the veneer sheets emerging from the screen beltconveyor,

said laminating conveyor means comprising means applying heat andpressure to the covering sheets and veneer sandwiched therebetween,thereby to activate the bonding adhesive and the thermoactive fillmaterial.

9. The apparatus defined in claim 8, wherein the laminating conveyormeans comprises rollers between which the assembled veneer and coveringsheets pass and are pressed, and means applying heat to the veneer andcovering sheets in conjunction with pressing the same together betweensuch rollers.

10. Apparatus for patching holes in veneer with particulatedthermoactive fill material, comprising support means including a veneerconveyor screen having a generally horizontal stretch and means mountedabove said stretch of screen to apply suction through the same to drawand hold the veneer sheet into contact with the lower side thereof overa surface area on the veneer including the area of holes to be patched,the screen mesh openings being smaller effectively than the size of saidparticulate material, applicator means for fill material stationedbeneath said screen stretch and operable for applying particulated fillmaterial to the veneer sheet to fill any holes in the veneer, saidapplicator means comprising a ,bin containing fill material extendingsubstantially the width of the screen, an agitator means in said binincluding a rotatable shaft extending transversely of the screen andhaving arms thereon dipping into the fill material in the bin andflinging such material upwardly in a steady shower against the lowersurface of the veneer as the shaft rotates accompanying advance of theveneer on the conveyor screen, heater means stationed beneath and spacedfrom said screen stretch at a relative location offset from saidapplicator means to heat the fills in the veneer superficially in thelower side thereof while held by suction on said screen, means to movethe screen and thereby the veneer successively past said applicatormeans and heating means, auxiliary veneer support means stationedadjacent said conveyor screen and offset from said heater means forreciving the veneer on transferral from the latter, and heating meansassociated With said auxiliary support means further to heat and curethe preliminarily heated fills, including the upper sides thereof, toactivate and substantially solidify the fill material therein.

Merritts et al Mar. 14, 1905 Valtat Oct. 7, 1930 1 Carlson Nov. 19, 1940Welch Apr. 29, 1947 Lambert et a1 as. 13, 1949 Elrnendorf Apr. 22, 1952McCullough et al. Mar. 3, 1953 Hogg Oct. 11, 1955 Seymour Nov. 29, 1955Grangaard et a1 Nov. 13, 1956 Runton Dec. 10, 1957 Works et a1 Nov. 18,1958

1.A CONTINUOUS METHOD OF PATCHING VENEER TO PLUG A HOLE THEREIN COMPRISING THE STEPS OF APPLYING A FERFORATE ETERNAL BACKING SURFACE TO THE UPPER FACE OF SAID VENEER, APPLYING A SUCTION TO SAID VENEER THROUGH SAID EXTERNAL BACKING SURFACE TO MAINTAIN SAID VENEER IN CONTACT WITH SAID BACKING SURFACE, PROPELING PARTICULATE THERMOACTIVE MATERIAL UPWARDLY FROM BENEATH SAID VENEER TO FILL SAID HOLE IN SAID VENEER WITH ENOUGH OF SAID MATERIAL TO COMPLETELY FILL SAID HOLE WHEN SAID MATERIAL HAS BEEN ACTIVATED, HEATING SAID MATERIAL ON THE LOWER FACE OF THE VENEER DURING THE APPLICATION OF SAID SUCTION TO EFFECT AT LEAST PARTIAL SOLIDIFICATION THEREOF AT SAID LOWER FACE AND TO A LIMITED DEPTH TERMINATING SHORT OF SAID UPPER FACE IN CONTACT WITH SAID SURFACE, REMOVING SAID HEAT FROM SAID LOWER FACE, CONTINUING SAID SUCTION DURING FORMATION OF A RETENTIVE CRUST ON SAID MATERIAL CONTINUING SAID SUCTION UNTIL SAID VENEER IS DEPOSITED ONTO A LOWER SUPPORT, REMOVING SAID SUCTION AND SAID PERFORATE BACKING SURFACE FROM SAID VENEER, AND FURTHER HEATING SAID MATERIAL TO ACTIVATE SAID MATERIAL IN SAID HOLE, WHEREBY A SUBSTANTIALLY SOLID PLUG IS FORMED IN SUCH HOLE. 